An easy-installed auxiliary brake control system for driving practice of an automobile by means of an auxiliary brake actuator and two-component cables. The cables have an outer sheath portion and an inner cable portion. It connects an auxiliary brake actuator to a brake arm of the automobile. The auxiliary brake actuator rests on a floor of a passenger compartment of the automobile, without necessity of being secured to it. When an instructor acts on the auxiliary brake actuator, the brake arm is actuated through relative movement between the inner cable portion and the outer sheath portion of the cables. This system is significantly cheaper than prior arts, especially for installation, and damages on the automobile for installation are minimized.